Due to increases in data transmission rates in telecommunications systems, crosstalk has become a significant problem. Crosstalk may be defined as stray energy which is coupled from one signal line onto an adjacent signal line by either capacitive or inductive coupling. This crosstalk results in signal noise which interferes with the purity of the signal being transmitted.
A commonly used telecommunications wiring system is unshielded twisted pair wiring wherein pairs of wires are twisted about each other. The wires in a twisted pair carry related signals and are thus known as signal pairs. Each of the wires in a signal pair carries an equal but opposite signal; that is, the wires carry signals of the same magnitude which are respectively positive and negative. Since these signals are equal but opposite, they generate fields that are equal but opposite. In a twisted pair these equal and opposite fields cancel each other. Thus, little or no crosstalk can occur between one twisted pair and an adjacent twisted pair.
Crosstalk in unshielded twisted pair wiring systems primarily arises in the electrical connectors which provide an interface between successive runs of cable in a system. Industry standard electrical connectors for telecommunications systems include modular plugs and jacks. These connectors have terminals which are spaced closely together and parallel to each other, and this close and parallel arrangement is conducive to crosstalk between adjacent lines in different ones of the signal pairs. Further, the terminals in a modular plug are dedicated to specific ones of the twisted wires according to a known industry standard such as EIA/TIA-568. Therefore, ends of the wires must be arranged in a closely spaced parallel sequence in the plug, and these parallel ends are also conducive to crosstalk.
Prior art techniques for reducing crosstalk have focused primarily on modular jacks and on the circuit boards on which the modular jacks are mounted. Since crosstalk increases logarithmically as the frequency of the signal increases, the constant trend toward higher data transmission rates has resulted in a need for further crosstalk reduction which may be obtained by reducing crosstalk in the modular plug.
U.S. Pat. No. 5,571,035 discloses a modular plug electrical connector having a wire organizer, or load bar, which maintains the wires in an organized array in the connector in order to reduce crosstalk in the connector. The load bar has upper and lower surfaces with grooves, and each of the grooves receives both wires of a respective signal pair. This device increases the separation between wires of different signal pairs, thereby avoiding crosstalk which would otherwise occur between the wires of different signal pairs. Still, some crosstalk occurs between terminals in the modular plug. Also, crosstalk which occurs in the modular jack of a communications cable rises significantly at very high frequencies on the order of 200-300 MHz. There is a need for reducing crosstalk in a modular plug and for improving overall crosstalk performance in a communications system.